banan-os/kernel/kernel/Thread.cpp

#include <BAN/Errors.h>
#include <BAN/ScopeGuard.h>
#include <kernel/InterruptController.h>
#include <kernel/Memory/kmalloc.h>
#include <kernel/Memory/PageTableScope.h>
#include <kernel/Process.h>
#include <kernel/Scheduler.h>
#include <kernel/Thread.h>


namespace Kernel
{

	extern "C" void thread_userspace_trampoline(uint64_t rsp, uint64_t rip, int argc, char** argv, char** envp);
	extern "C" uintptr_t read_rip();

	extern "C" void signal_trampoline();

	template<typename T>
	static void write_to_stack(uintptr_t& rsp, const T& value)
	{
		rsp -= sizeof(uintptr_t);
		if constexpr(sizeof(T) < sizeof(uintptr_t))
			*(uintptr_t*)rsp = (uintptr_t)value;
		else
			memcpy((void*)rsp, (void*)&value, sizeof(uintptr_t));
	}

	static pid_t s_next_tid = 1;

	BAN::ErrorOr<Thread*> Thread::create_kernel(entry_t entry, void* data, Process* process)
	{
		// Create the thread object
		Thread* thread = new Thread(s_next_tid++, process);
		if (thread == nullptr)
			return BAN::Error::from_errno(ENOMEM);
		BAN::ScopeGuard thread_deleter([thread] { delete thread; });

		// Initialize stack and registers
		thread->m_stack = TRY(VirtualRange::create_kmalloc(m_kernel_stack_size));
		thread->m_rsp = thread->stack_base() + thread->stack_size();
		thread->m_rip = (uintptr_t)entry;

		// Initialize stack for returning
		write_to_stack(thread->m_rsp, thread);
		write_to_stack(thread->m_rsp, &Thread::on_exit);
		write_to_stack(thread->m_rsp, data);

		thread_deleter.disable();

		return thread;
	}

	BAN::ErrorOr<Thread*> Thread::create_userspace(Process* process)
	{
		ASSERT(process);

		// Create the thread object
		Thread* thread = new Thread(s_next_tid++, process);
		if (thread == nullptr)
			return BAN::Error::from_errno(ENOMEM);
		BAN::ScopeGuard thread_deleter([thread] { delete thread; });

		thread->m_is_userspace = true;

		thread->m_stack = TRY(VirtualRange::create(process->page_table(), 0, m_userspace_stack_size, PageTable::Flags::UserSupervisor | PageTable::Flags::ReadWrite | PageTable::Flags::Present));
		thread->m_interrupt_stack = TRY(VirtualRange::create(process->page_table(), 0, m_interrupt_stack_size, PageTable::Flags::UserSupervisor | PageTable::Flags::ReadWrite | PageTable::Flags::Present));

		thread->setup_exec();

		thread_deleter.disable();

		return thread;
	}

	Thread::Thread(pid_t tid, Process* process)
		: m_tid(tid), m_process(process)
	{}

	Thread& Thread::current()
	{
		return Scheduler::get().current_thread();
	}

	Process& Thread::process()
	{
		ASSERT(m_process);
		return *m_process;
	}

	Thread::~Thread()
	{
	}

	BAN::ErrorOr<Thread*> Thread::clone(Process* new_process, uintptr_t rsp, uintptr_t rip)
	{
		ASSERT(m_is_userspace);
		ASSERT(m_state == State::Executing);

		Thread* thread = new Thread(s_next_tid++, new_process);
		if (thread == nullptr)
			return BAN::Error::from_errno(ENOMEM);
		BAN::ScopeGuard thread_deleter([thread] { delete thread; });

		thread->m_is_userspace = true;

		thread->m_interrupt_stack = TRY(m_interrupt_stack->clone(new_process->page_table()));
		thread->m_stack = TRY(m_stack->clone(new_process->page_table()));

		thread->m_state = State::Executing;
		thread->m_in_syscall = true;

		thread->m_rip = rip;
		thread->m_rsp = rsp;

		thread_deleter.disable();

		return thread;
	}

	void Thread::setup_exec()
	{
		ASSERT(is_userspace());
		m_state = State::NotStarted;
		static entry_t entry_trampoline(
			[](void*)
			{
				const auto& info = Process::current().userspace_info();
				thread_userspace_trampoline(Thread::current().rsp(), info.entry, info.argc, info.argv, info.envp);
				ASSERT_NOT_REACHED();
			}
		);
		m_rsp = stack_base() + stack_size();
		m_rip = (uintptr_t)entry_trampoline;

		// Setup stack for returning
		{
			// FIXME: don't use PageTableScope
			PageTableScope _(m_process->page_table());
			write_to_stack(m_rsp, this);
			write_to_stack(m_rsp, &Thread::on_exit);
			write_to_stack(m_rsp, nullptr);
		}
	}

	void Thread::handle_signal(int signal, uintptr_t& return_rsp, uintptr_t& return_rip)
	{
		ASSERT(signal >= _SIGMIN && signal <= _SIGMAX);
		ASSERT(&Thread::current() == this);

		// Skip masked (ignored) signals
		if (m_signal_mask & (1ull << signal))
			return;

		if (m_signal_handlers[signal])
		{
			asm volatile("cli");
			write_to_stack(return_rsp, return_rip);
			write_to_stack(return_rsp, signal);
			write_to_stack(return_rsp, m_signal_handlers[signal]);
			return_rip = (uintptr_t)signal_trampoline;
		}
		else
		{
			switch (signal)
			{
				// Abnormal termination of the process with additional actions.
				case SIGABRT:
				case SIGBUS:
				case SIGFPE:
				case SIGILL:
				case SIGQUIT:
				case SIGSEGV:
				case SIGSYS:
				case SIGTRAP:
				case SIGXCPU:
				case SIGXFSZ:
					// TODO: additional actions
					// fall through

				// Abnormal termination of the process
				case SIGALRM:
				case SIGHUP:
				case SIGINT:
				case SIGKILL:
				case SIGPIPE:
				case SIGTERM:
				case SIGUSR1:
				case SIGUSR2:
				case SIGPOLL:
				case SIGPROF:
				case SIGVTALRM:
				{
					auto message = BAN::String::formatted("killed by signal {}\n", signal);
					(void)process().tty().write(0, message.data(), message.size());
					process().exit(128 + signal);
					ASSERT_NOT_REACHED();
				}

				// Ignore the signal
				case SIGCHLD:
				case SIGURG:
					break;

				// Stop the process:
				case SIGTSTP:
				case SIGTTIN:
				case SIGTTOU:
					ASSERT_NOT_REACHED();

				// Continue the process, if it is stopped; otherwise, ignore the signal.
				case SIGCONT:
					ASSERT_NOT_REACHED();
			}
		}

		asm volatile("cli");
		if (!m_signal_queue.empty() && m_signal_queue.front() == signal)
			m_signal_queue.pop();
	}

	void Thread::validate_stack() const
	{
		if (stack_base() <= m_rsp && m_rsp <= stack_base() + stack_size())
			return;
		if (interrupt_stack_base() <= m_rsp && m_rsp <= interrupt_stack_base() + interrupt_stack_size())
			return;
		Kernel::panic("rsp {8H}, stack {8H}->{8H}, interrupt_stack {8H}->{8H}", m_rsp,
			stack_base(), stack_base() + stack_size(),
			interrupt_stack_base(), interrupt_stack_base() + interrupt_stack_size()
		);
	}

	void Thread::on_exit()
	{
		if (m_process)
			m_process->on_thread_exit(*this);
		Scheduler::get().set_current_thread_done();
		ASSERT_NOT_REACHED();
	}

}